This invention relates generally to apparatus for joining sheets of roofing material, and in particular to an improved handroller for both press-welding and/or sealing overlapping edges of such sheets together.
Pliable sheets of sealable materials are commonly used in many industrial, environmental and civil construction applications, especially the roofing industry. Sealable materials used in the roofing industry generally use one of three types of seams for joining the sealable materials, i.e., heat seal, adhesive/bond seal, and self-adhesive seal. Typically, in a roofing application, large sheets of materials are placed on the roof with their edges overlapping. For instance, a single-ply thermo-plastic sheet is often utilized as a roofing membrane to prevent leakage of water through a roof. When using adhesive/bond or self-adhesive seals, the overlapping edges are press-welded to one another. When using thermo-plastic materials, the overlapping edges are heat welded to one another along or within the overlap. The heat sealing process is done manually by an artisan who separates the overlapping edges along the overlap and then heats the separated edges, e.g., by directing hot air between the separated edges with a blow gun or hot air device. When heated sufficiently, the surfaces of the separated edges liquify. The edges are then pressed together to provide a seam or tack-weld between the overlapping edges which joins the sheets together when it cools. Typically a moveable compressing means such as a handroller is used to press the edges together, regardless of the type of seams used.
An example of a roofing method using thermally sealable materials is disclosed in U.S. Pat. No. 4,894,112, issued to Glenn W. Lippman on Jan. 16, 1990, said patent being incorporated herein by reference. Referring to the Lippman patent, specifically FIGS. 4, 5 and 6, there is disclosed a typical prior art handroller used in the above-described roofing method. This is also the standard roller used for joining any of the three general types of seams in use in the roofing industry. The handroller 100 is comprised of a cylindrical handle with a single roller 101. The roller 101 is made of silicone rubber for heated seams, and metal or silicone rubber for adhesive/bond and self-adhesive seams. The handroller 100 is used to seal or weld overlapping edges of sealable materials together, which sheets are laying on a surface. To maximize the application of downward force and yet move the handroller, the handroller is preferably held at an approximate 45.degree. angle. This angle may vary, however, anywhere from 30.degree. to 90.degree. depending upon the strength of the artisan using the handroller and the amount of pressure needed to press the sheets together. When sealing materials require substantial pressure, it may be necessary to hold the prior art handroller at an angle approaching 90.degree..
As may be seen from the Lippman patent, especially FIG. 4, the application of the handroller to the edges requires a reasonable amount of strength in the artisan's wrist and forearm. Regardless of the artisan's strength, over time, e.g. a workday, the relentless pressing down on the handroller will substantially weaken the artisan's strength. From a practical point of view, the inventor has found that edges and seams treated toward the end of a workday are considerably inferior to those treated nearer to the beginning of the workday. Artisans in this field also experience chronic muscle fatigue, i.e., tendinitis, especially in their wrists and forearms.